The model contains one compartment called C. There are three species called S1, S2 and S3 and two parameters called k1 and k2. The model contains two reactions defined as:
Reaction | Rate |
S1 + S2 → S3 | k1 · S1 · S2 · C |
S3 → S1 + S2 | k2 · S3 · C |
The model contains two events that assign values to species S2 and S1:
Trigger | Delay | Assignments | |
Event1 | lessthan(S1, 0.6) | − | S2 = 1.5 |
S1 = add(k3, k4) |
Both the event trigger and assignment use functionDefinitions defined as:
Id | Arguments | Formula | add | x, y | x + y | |
lessthan | x, y | x < y |
The initial conditions are as follows:
Value | Units | |
Initial amount of S1 | 1.0 | mole |
Initial amount of S2 | 2.0 | mole |
Initial amount of S3 | 1.0 | mole |
Value of parameter k1 | 0.75 | litre mole-1 second-1 |
Value of parameter k2 | 0.25 | second-1 |
Value of parameter k3 | 0.5 | mole litre-1 |
Value of parameter k4 | 0.5 | mole litre-1 |
Volume of compartment C | 1 | litre |
The species values are given as amounts of substance to make it easier to use the model in a discrete stochastic simulator, but (as per usual SBML principles) their symbols represent their values in concentration units where they appear in expressions.